Christopher Plummer's character in 'Beginners' experiences a tremendous rejuvenation later in life. Kind of like the actor, 81, feels in his own life.

Like autumn leaves that blaze brightest before they fall, the performance given by Christopher Plummer in "Beginners" reminds one that life can sometimes save the best for last. In the charming comedy-drama from writer-director Mike Mills, Plummer plays Hal, a widower who waits until his wife of 45 years dies to tell his son, Oliver (Ewan McGregor), that he's gay.

And from that point on, he's the happiest person in the story — even after he's diagnosed with terminal cancer. "It's because he's found himself. He's free from all that burden of trying to suppress his homosexuality, and he's also in love," Plummer says. "I think that's why the film has the lightness of tone that it does — there's not an ounce of self-pity in it."

Hal, a retired museum director, acquires a bright neckerchief and a circle of new party-loving friends, and he sets out to make the most of his remaining time. Because the film weaves together two stories — the other is about Oliver's attempt to forge his first lasting romance, with an actress (Mélanie Laurent) — Plummer's screen time is fairly brief. But he makes the most of it. "As a writer, Mike filled those scenes with a lot of emotional color and humor, so they seem more major than they are," Plummer notes. "But I know how to color a role too — by God, I ought to by now. In film acting, it's all about the eyes and what you're thinking."

As Hal, Plummer conveys a roguish twinkle and a giddy joy whenever his younger boyfriend, the goofy, lumbering Andy (Goran Visnjic of "ER") is near. He's played a gay man only once before — in the 1980 television film "The Shadow Box," directed by Paul Newman — but says the assignment didn't rattle him. "After all, when you play homosexual, you just play the man, and he's very human and relatable," he says of Hal. It was Visnjic who confessed to nerves. "He's this great bruiser of a guy, and he kept saying, 'We have to kiss tomorrow, damn it.' It was fine, we did it; we're actors after all."

"Beginners" also has its poignant moments — when it starts, Hal lies in a hospital bed, so confused that he asks his son whether he is married to the nurse. But for the most part, it offsets its melancholy with an open-hearted embrace of life's curveballs.

Plummer says this is what drew him to the script, which Mills based on the story of his own father's late-life coming-out. "It was so unusual, and yet so touching and full of heart," he notes.

He brought much of himself to the screen. At 81, he's enjoying a late-career renaissance. In September, the movie "Barrymore" — a filmed version of his Tony-winning stage role as the American acting great John — premiered to rave reviews at the Toronto Film Festival. In 2009, he received a supporting actor Oscar nomination for "The Last Station," in which he played novelist Leo Tolstoy. A position Plummer could well find himself in again this Oscar season.

"Hal is a very grateful man, as indeed I am, as I approach senility," Plummer jokes. "And I'm finding this part of life to be a great period of discovery. After all, you ain't got much time left, so you've got to discover things while you can."

The Canadian-born actor, perhaps best known for his role as Captain Von Trapp in "The Sound of Music," honed his craft on the New York stage in the 1950s, during the golden era of American drama, and in London in the 1960s, when he performed with the Royal Shakespeare Company and the National Theater, essaying "many of the greatest parts ever written."

Even so, his favorite period, he proclaims with some surprise, is now. "I'm working harder and more frequently than I've ever worked. And it keeps me young."

Next month, he'll be seen in David Fincher's American remake of "The Girl With the Dragon Tattoo," in which he plays retired industrialist Henrik Vanger. Plummer says he knows the highly anticipated, $100-million production is likely to make quite a splash. But it's performing in smaller, independent films like "Beginners" that interests him most. "Those are the ones that matter," he says. "They stick their necks out and take risks."